Refrigerating apparatus



O. M. SUMMERS REFRIGERATING APPARATUS 4Filed DSC. 3l, 1929 May l2, 1931.

IN VEN TOR m, ATTORNEY Patented May l2, 191

UNITE ATuNr lOFFICE OTTO M. SU, OF DYTN, OHIO, ASSIGNDR TO FRIGIDAIRE CORPORATION, 0F

DAYTN', DMO, .A COEPGB/ATION 0F DELAWARE REFRIGERATING APPARATUS Application led December 81, 1929. Serial No. 417,705.

This invention relates to refrigerating apparatus and more particularly to the evaporator or low pressure side of refrigerating apparatus.

' 5 An object of this invention is to provide improve means for maintaining a minimum amount of liquid other than refrigerant om the low pressure side of the refrigerating system.

Another object of the present invention isy to provide for the flow of such liquid from the evaporator by gravity and to utilize the change in pressure, due to the change' in temperature of the evaporator, for controlling the flow of such liquid from the evaporator.

In carr ing out the above objects, it is a further o ject to provide means for and a method of returning such liquid only during the latter part of the operating cycles of the refrigerating system.

Further objects and advantages of the present invention will be apparent from the following description, reference being had to the accompanyin drawings, wherein a preferred form of t e present invention is clearly shown.

In the drawings:

Fig. 1 is a vertical section throu h a porao tion of an evaporator having my invention embodied therein and having a refrigerating system shown diagrammatically adapted to be connected with the evaporator; and

\ Fig. 2 is a fragmentary sectional view 85 taken on lines 2-2 of Fig. 1.

In Fig. lis disclosed diagrammatically a portion of a refrigerating system comprising a compressor 10 for compressing the refrigerant, preferably sulphur dioxlde, and

for forwarding it to the condenser 11 where it is liquefied andcollected in the receiver 12. The actuating means for the compressor preferably comprises a motor 13 connected by pulley and belt means 14 to the compressor.

l A supply conduit 15 supplies li uid refrigerant to the evaporator throng the inlet connection 25 and a return conduit 16 connected to' a gaseous refrigerant outlet connection 24 returns the refrigerant vapor from the evaporator to the compressor 10.

A pressure responsive switch means 17 is preferably connected in the return conduit 16 for controlling the motor 13 to provide alternating operatino' and idle periods of the compressor according to the pressure and consequently the temperature of the evaporator.

The preferred type of evaporator as -disclosed in the drawings comprlses a boiler 0r tank 20, preferably of a cylindrical form, 6o having its end closed by a valve plate 21 secured in a supporting ring 22 by the screws 23 surrounding the opening in the boiler 20. The valve plate 21 has the gaseous refrig-v erant valve 24 and the liquid refrigerant 65 inlet valve 25 supported thereon. vThe inlet valve 25 for the liquid refrigerant enters into a gradually restricted passage through a boss 26 on the innerside of the valve plate. A supporting bracket 27 is attached to this 70 boss and supports a oat ball 28 and float ball arm 29 operating the needle valve 30 for controlling the flow of liquid refrigerant into the evaporator.

The outlet valve 24 preferably communi- 75 cates through the valve plate to an outlet tube 31 having an open end 32. Attached to this open end 32 is a casing 33 having an open upper end 34. In this open upper end is a screw'threaded nut 35 having an open 8c portion 36. The bottom ofthe casing 33 is provided with an opening and has a'valve 37 seated in this opening. A spring 38 preferably bears against the top of the valve and the under side ofthe nut 35 and tends to 85 keep the valve seated. The pressure of the spring can be adjusted bythe nut 35. The

valve 37 is connected to and controlled by a ly the tem erature within the evaporator between pre etermined limits. When the pressure within the evaporator rises to the high limit corresponding to the high temperature limit required, the motor is started and the compressor withdraws refrigerant gas from the evaporator through the opening 36, tube 31, outlet connection 24 and suction line 16. The gas is compressed in the compressor and forced into the condenser 11 where it is condensed and collected in the receiver 12. From the receiver the liquid refrigerant flows to the evaporator within which a constant quantity thereof is maintained by the float 28 operating the inlet valve 30.

The bellows 39 controlling the valve 37 is set to open at a pressure slight-ly greater than the pressure required to stop the compressor, and to remain closed above this point. During the operation of the compressor, lubricant is circulated through the system with the refrigerant and means for returning t-he lubricant from the evaporator must be provided, otherwise the evaporator will become less efficient. This lubricant collects in a layer on the top of the liquid refrigerant and consequently when the valve 37 opens just before the compressor'stops, the lubricant above the valve opening 37 flows back to thecompressor crankcase. It will be understood, that the opening in the casing 33 is positioned. slightly above the normal liquid refrigerant level so that no liquid refrigerant will be returned to the compressor.

Further by opening the valve 37 only just before the stopping of the compressor, the liquid refrigerant will not be boiling violently and consequently the lubricant may be removed easily and without carrying any liquid refrigerant mixed therewith.

While the device has been shown as removing lubricant from the top surface of the liquid refrigerant it is equally applicable for removing lubricant heavier than refrigerant by merely providing an extension conduit leading from the opening 37 to a point near the bottom of the eva orator.

It will be noted that the open upper 1end 32 of the casing 33 is adjacent the top of the tank 20 and therefore lubricant will ynot readily ilow from the evaporator at this point. This is advantageous in that, if lubricant were permitted to escape while the boiling is violent, a certain amount of liquid refrigerant would be carried with the lubricant causing refrigeration outside the evaporator.

It is thus apparent that by the present invention I have provided for the return of lubricant when an excessive amount collects in the evaporator and I have arranged for the return of lubricant to the compressor when the boiling in the evaporator is less violent.

Preferably part of the air is withdrawn from bellows 39, but it is to beunderstood that various pressures may be maintained therein and iiuids other than air, and springs can be used to suit the requirements of different operating conditions of the evaporator.

While the form of embodiment of the invention as herein disclosed, constitutes a preferred form, it is to be understood that other forms might be adopted, all coming within the scope of the claims which follows.

What is claimed is as follows:

1. A refrigerating system including an evaporator and a refrigerant supply unit for supplying liquid refrigerant to said evaporator, a lubricant adapted to accompany said refrigerant to said evaporator, means for operating said refrigerant supply unit in cycles, V

means to withdraw excess lubricant from said evaporator during the latter part only of the operating cycle of the refrigerant supply unit comprising an outlet conduit having an opening in its upper portion for the passage therethrough of evaporated refrigerant and an opening in its under portion for said oil, and a valve opening and closing said last mentioned opening.

2. A refrigerating system including an evaporator anda refrigerant supply unit for supplying liquid refrigerant to said evaporator, a lubricant adapted to accompany said refrigerant to said evaporator, means for operating said. refrigerant supply unit in cycles, means to withdraw excess lubricant from said evaporator during the latter part only of the operating cycle of the refrigerant supply unit comprisin ing an opening in its upper portion for the passage therethrough of evaporated refrigerant and an opening in its under portion for said oil, a valve opening and closing said last mentioned opening, and pressure responsivle means in said evaporator controlling said va ve.

3. In refrigerating apparatus utilizing as a working fluid a refr? 'erant and a lubricant which separate by gravity, means for maintaining a substantially constant quantity of liquid refrigerant in the evaporator, means for removing by ravity the lubricant collecting on the sur ace of the liquid refrigerant in the evaporator, said means including a valve disposed at the lubricant level desired to be maintained in the evaporator, and means responsive to conditions within said evaporator for operating said valve.

4. In refrigerating apparatus utilizing as a working fluid a lubricant and a refrigerant which separate in the evaporator by gravity, an evaporator means for supplying refrigerant and lubricant to said evaporator and means having a portion disposed at the lubricant level desired to be maintainedv in the eva orator and responsive to conditions within t eevaporator causing the return by gravan outlet conduit hav-l ity of separated lubricant to the first named means.

5. In rerigerating apparatus u M as a working fluid a lubricant and a refrigerant which separate by gravity in the evaporator, an evaporat,or,`means for supplying lubri-` cant and refrigerant to said evaporator, means causing the return by gravity of the lubricant from the evaporator to said rst named means, said means including a valve disposed at the lubricant level'desired to be maintained in the evaporator2 and miresponsive to the pressure within the evaporasignatureE tor for operating said valve.. v

6. In rerigerating apparatus utilizing as a Working Huid a mixturedo refrigerant and lubricant capable of separatin by vity, an evaporator, a compressor an a condenser connected in a closed cycle, a motor for driving said compressor, means responsive to the pressure Within' said evaporator for startn and stopping said motor at predetermin high and low pressures within said evaporator, means for returning lubricant by gravity from the evaporator to said compressor'including valve. means, means responsive to the pressure within the evaporator for opening and closing said valve, said last named means being eective to open said valve at a pres- .suresli htiy in excess of that required to sto ,sai motor.

testimony whereof fhgereunto 1 or'ro n.. sns.

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